Book/Report

FZJ-2018-02905

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Untersuchungen zur Ionisation von abgestäubtem Titan und zum Transport der Titanionen in einer Argon-Glimmentladung mittels laserinduzierter Fluoreszenz

Koppmann, R. (Corresponding author)FZJ*

1988
Kernforschungsanlage Jülich, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/18534

Report No.: Juel-2219

Abstract: The ionisation mechanism for sputtered titanium and the transport process of the titanium ions were investigated in an Argon glow discharge using laserinducedfluorescence spectroscopy. The density profiles of neutral titanium showed a maximum near to the cathode with densities of some 10$^{11}$ cm$^{-3}$ and a decrease of more than one order of magnitude towards the anode. The shape of the profile can be described by a model considering thermalisation and diffusion processes. For the first time the density distribution of singly ionized titanium was measured in the axis of a glow discharge. The density profiles of Ti$^{+}$ showed a maximum located on diffusion dominated side of the corresponding Ti$^{0}$-profile with maximum densities of 1$\cdot$10$^{9}$ cm$^{-3}$. Towards the cathode the density of Ti$^{+}$ decreased rapidly, the decrease towards the anode followed the Ti$^{0}$-profile. The titanium ionisation degree of 10$^{-2}$ lead to the assumption that Penningionisation is the dominant ionisation process for the sputtered titanium atoms. A comparison of the ionisation rate at given glow discharge parameters showed that Penning-ionisation is by a factor of 104 more effective than electron impact ionisation. The overpopulation of the upper ground state levels of Ti$^{+}$ is also an indication for Penning-ionisation because the excited Ti$^{+}$-levels resulting from the Penning process decay preferably into these levels. From a balance of the Ti$^{0}$ and Ti$^{+}$ fluxes on the axis of the discharge it was possible to calculate the axial electrical field strength. The results reveal an almost constant field strength of $\approx$ 3V/cm in the positive column and an increase towards the cathode. The measurement of the shift of the Ti$^{+}$ velocity distribution gave a drift velocity of the titanium ions of 5.5$\cdot$10$^{4}$ cm/s at a cathode distance of z = 13.8 mm and 9.4$\cdot$10$^{4}$ cm/s at z = 10.8 mm. With the given mobility of Ti$^{+}$ the electrical field strength at these positions was calculated. The results agree within the error of measurement with the field derived from the flux balance.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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